Chrysler 440 weird miss (with video)

[Chassisman]

Since you converted it to Petronix.....plug the vac advance..... set it to 28 degrees total timing and forget it. Mopars HATE vac adv. once you go to electronic ignition......I chased the same thing on my 65 Coronet when I changed from points to Petronix ...unplugged.....hauled ass....never looked back.

[Caveman Tony]

Couple other random ideas....

Dizzy cap new or old? Could be arcing inside the cap or grungy/corroded inside.

Cracked spark plug porcelain?

Maybe some carbon buildup on a few valves? dunno, just a wild-ass guess on that...



does it ever backfire?

[TomP]

Chrysler 440 weird miss

Thanks to all for the input. It has been very helpful in smoothing out the engine.
The issue started after hitting the gas hard on the way home from Brians. The car was running the original Carter AVS carb and original ignition distributor/points at the time. I added the Pertronix as an upgrade - no difference. Suspecting a vacuum leak at throttle shafts, I replaced the carb with an edelbrock and this made a big difference by eliminating the stumble and smoothing the idle. The engine runs smooth but will drop off from idle (200-300 rpm drop) when shifting into gear. It will run smooth even below 500 in neutral but once a load is applied it drops right off. I need to set the idle at 850-900 to minimize or avoid the miss/stumble Brian discribed. The car runs strong while cruising as well.
I will be checking the timing chain/TDC tonight in case the hard accelleration lossened something up. It is also a good time to install an old Edelbrock CH4B manifold in case I missed a vacuum leak at the manifold.
Thanks again for helping us figure this out. Tom

[BKBridges]

Tom,
I didnt know it happened after a "blast". Check your pushrods out to make sure one didnt bend. 440s do this occasionally...Hmmm... In fact the past 3 Ive worked on had bent pushrods. New larger dia pushrods help eliminate this problem. The pic doesnt show it very well, but when you spin the pushrods in place its pretty obvious! The owner of this car had no idea other than a rough idle. His carb was so messed up (Thermoquad) performance wasnt much affected...
Bruce

[TomP]

BK, Appreciate the input on the pushrods. I will be checking them carefully when I pull the manifold this weekend. Thanks, Tom

[Stich496]

BK, Appreciate the input on the pushrods. I will be checking them carefully when I pull the manifold this weekend. Thanks, Tom

a plate of glass is great for checking pushrods.. bet more than one's took a bend

[DanStokes]

Sounds like you're on your way to a happy motor. I've run CH4Bs on a couple of engines to good effect. There are newer, better designs out there but I think it's still a good piece.

Mostly I'm amazed that you let your beautiful daughter hook up with that Bozo! Now that there are kids involved I suppose you're stuck with him. (Just teasin', Brian. You know I love ya!).

Dan

[Brian Lohnes]

Easy Dan!

The CH4B works best in this scenario because it allows the use of the factory air grabber setup on the car. The height of most other intakes does not allow the Air Grabber to be kept in place.

The car still has a little miss to it at idle, Tom did check the pushrods and they looked OK. He had some suspicions about the dist he was going to investigate, but he did tell me that the car has been running a lot better of late.

[TC]

Bad gas??

[Scott Liggett]

Easy Dan!

The CH4B works best in this scenario because it allows the use of the factory air grabber setup on the car. The height of most other intakes does not allow the Air Grabber to be kept in place.

The car still has a little miss to it at idle, Tom did check the pushrods and they looked OK. He had some suspicions about the dist he was going to investigate, but he did tell me that the car has been running a lot better of late.

I think DF did a 440 intake comparo during the Carjunkie days. That ole CH4B held it's own against the newer designs, even besting a few.

My cars have noticeably started running like dog turds now they got their first tank of the summer blend toilet water. The Impala is especially unhappy.

[TomP]

Chrysler 440 weird miss

After some fiddling with the idle mixture and some timing adjustments the engine is running real smooth and strong. It still drops off 100+ rpm in gear but stays steady. (low stall torque converter?) The CH4B fit great with about 1/2 inch hood clearance under the air grabber and the carb is super smooth while cruising. Luckily the push rods were nice and straight and TDC was dead on. I hate to admit it but for some reason I mis-marked the timing mark when putting the engine together (two years ago) so I had been running at TDC instead of 5 degree before. Anyway with the 42 year old carb that went lean, the idiot who neatly applied the timing mark on the wrong line, a lean mix and bad gas fixed things are looking up.
Thanks again for all the help. It was great working on a car again and it is nice to get out and cruise with Goliath. Tom

[Scott Liggett]

Old cars need to be upjetted to run on today's methanol laiden gas. I've had to do this to a half dozen cars. Going up in the plugs heat range really helps my junk heaps.

[TomP]

I am definately with you on this Rebeldryver. I recall draining the carter an thinking this is gas? It looks more like a non volitile syrup. Thanks for the advice on plugs. It looks like I will be dumping some old J10 and J11Ys I've got kicking around.